A number of textile products have been described for applications including bedding, apparel, hygiene and toys in which microencapsulated thermochromic pigments are incorporated into synthetic fibres as a dispersed phase (e.g. U.S. Pat. No. 6,444,313 and US patent application 2003/0087566), or as a coating on the surfaces of the fibres using a binding medium (e.g. U.S. Pat. No. 4,681,791). Thermochromic yarns, fabrics and garments are also disclosed in Japanese patent publications 59144613 and 4756267. Japanese patent publication 48044522 discloses composite fibres containing cholesteric liquid crystals.
US patent application 2008/0279253 discloses thermochromic garments to track body temperature regulation of patients and children for use by clinicians, parents and caregivers. The garment contains at least two thermochromic dyes or colourants, each being sensitive to a different temperature range. This provides a facility to identify whether a body is overheating or is too cool, or to ascertain whether a heating or cooling device is working sufficiently. Described embodiments include the addition of mincroencapsulated leuco dyes into polymer fibrous webs by melt blowing techniques. Another garment incorporating thermochromic pigments or thermochromic strip thermometers is described in US patent application 2009/00467760. The garment is proposed as a means of providing early detection and prevention of cold exposure to skin surfaces, or venous insufficiencies.
There have been a range of disclosures of medical or clinical applications for thermochromic liquid crystalline materials. In U.S. Pat. No. 5,806,528, such materials are proposed as temperature indicators for fluids intravenously delivered to patients, to ensure that they are not at a temperature that is either uncomfortable or harmful to a patient. US patent application 2011/0028804 discloses a topical product that exhibits thermochromic behaviour when applied to the skin. The product is intended to be used for diagnosing the onset of conditions such as necrosis and decubitus ulcers in the skin of a patient, by identifying increased temperatures due to inflammation present in the early stages of ulcer formation. The topical product is described as being a liquid and is possibly applied as a spray. The patent application suggests the use of either liquid crystalline mixtures or leuco dyes as a thermochromic component, dispersed into a body lotion or soap.
U.S. Pat. No. 5,181,905 discloses a wound dressing containing a thermochromic indicator for monitoring the condition of an underlying wound while the dressing is being worn. The thermochromic component is in the form of a temperature sensitive liquid crystal tape that has a plurality of labelled boxes containing liquid crystalline mixtures tuned to appear coloured at different temperatures. Temperature determination is dependent on which box or boxes appear coloured while the dressing is being worn.
U.S. Pat. No. 4,433,637 describes a thin flexible sheet coated with liquid crystals, microencapsulated or otherwise, over a black backing as a means for measuring temperatures of the surface of the skin.
It is an object of the invention, at least in one or more aspects, to provide a novel and useful composite sensor fibre.
Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.